Hearing aid devices are provided in different power classes. These are differentiated, in particular, by the respective type of receiver used, on which the maximum power output and the maximum sound pressure level able to be produced depend. In hearing aid devices which may be worn behind the ear, in which the receiver, when the hearing aid device is worn, is located in an earpiece in the ear canal of the user, so-called RIC-BTE (Receiver-in-Canal-behind-the-Ear) hearing aids, hearing aids of varying performance may be produced in a simple manner by the use of different earpieces with different receivers.